Not having double copies of your files

Hi, I’m new (as you can tell) and my dad bought me a WD external hard drive thing for me from Best Buy (I guess they were on sale) for me to use with my MacBook… anyways… I have to go to the Genius Bar tomorrow to fix my laptop and needless to say I’ve had quite many experiences where the people at Apple just delete my entire hard drive and I’m thinking ahead and trying to back up my computer just in case.

I have previously backed up my MacBook once and I was wondering how do you go about just adding new files to the ones you’ve replaced and not go about having doubles of everything (2 of the same songs, etcetc). Sorry this is a pretty stupid question but I’m actually clueless and don’t know what to do… I don’t want to lose any of the pictures, documents, and songs I originally backed up because I’ve deleted them from my current laptop but how do i just add the “new” stuff not previously on my MacBook onto the external (without having to DRAG each individual file to the hard drive to “copy”?

There must be an easier way because right now… I’m copying my entire MacBook over to the external. :\


And thanks in advance!!

Did you ever get your answer?

I am having the same problem with my Passport Essential external HD.  I don’t need multiple copies of my computer.